42 lines
895 B
Java
42 lines
895 B
Java
/*
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* @lc app=leetcode id=141 lang=java
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*
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* [141] Linked List Cycle
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*/
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// @lc code=start
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/**
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* Definition for singly-linked list.
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* class ListNode {
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* int val;
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* ListNode next;
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* ListNode(int x) {
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* val = x;
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* next = null;
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* }
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* }
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*/
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public class Solution {
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/**
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* 快慢指针，若链表中存在环，则快指针一次动两步，慢指针一次动一步，快指针一定会赶上慢指针
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*
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* @param head
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* @return
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*/
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public boolean hasCycle(ListNode head) {
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ListNode slow = head, fast = head;
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boolean isCycle = false;
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while(fast != null && fast.next != null) {
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fast = fast.next.next;
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slow = slow.next;
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if(fast == slow) {
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isCycle = true;
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break;
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}
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}
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return isCycle;
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}
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}
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// @lc code=end
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